Pumping unit with spring connected walking beam



Nov. 5, 1963 3,109,313

PUMPING UNIT WITH SPRING CONNECTED WALKING BEAM Filed Dec. 11, 1961 4/-.

25 JOHN EDWARD LOTT 25 33g INVENTOR I0 q BY [Zw FIG. 2.

A TTORNE Y United States Patent M 3,109,313 PUMPING UNIT WITH SPRHJG (IONNECTED WALKING BEAM John Edward Lott, Fort Worth, Tern, assignor to American Manufacturing Company of Texas, Fort Worth, Tex., a corporation of Texas Fiieri Dec. 11, 19(11, Ser. No. 158,518 6 Claims. (Cl. 74-41) This invention relates to well pumping units of the beam type and has reference to an improved linkage between the speed reducer and the polished rod.

Heretofore, pumping units of the beam type employed a four bar linkage (four pivot points) which would theoretically reach its maximum efiiciency if the samson post were of infinite height. To make the samson post of greater than standard height would have economic limitations and would present problems of assembly in the held. In recent years manufacturers of pumping units have recognized the value of higher geometric efficiencies and many have designed taller samson posts which resulted in higher pitman lengths to crank radius ratios and thus improved geometric efliciency. Necessarily, the included angularity of the pitrnan decreases with the lengthening of the eifective pitman length and improves the geometric efliciency. Any increased angularity of the pitman results in a higher crank wrist pin load by reason of the foreshortening of the pitmans effective leverage arm in relation to the load at the polished rod. The locations of the speed reducer and tail bearing have been shifted in various ways to improve geometric efficiency; however, advantages gained by such shifting generally resulted in a mechanism that operated to an advantage only in one direction of crank rotation. Heretofore, such variations, that is, increased height of sampson post and shifting of speed reducer or tail bearing, increased geometric efiiciency to a value below 100 percent.

The primary object of the invention is to provide 100% geometric efficiency in a beam type pumping unit.

Another object is to provide perfect torque factors wherein the maximum torque load is limited to the prodnot of one-half the stroke length multiplied by the polished rod load.

Additional objects include the elimination of certain wearing parts, namely, tail bearing, oil seals and flexible lubrication lines.

These and other objects of the invention will become apparent from the following description and the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of a pumping unit incorporating the invention.

FIGURE 2 is an end elevational view of FIGURE 1.

FIGURE 3 is a broken perspective detail of the invention.

FIGURE 4 is a broken end elevational view of an equalizer beam showing a modified form of the invention.

The pumping unit illustrated is conventional with respect to its general construction including a base frame 10, a samson post 11 and a walking beam 12 mounted on the samson post by means of a saddle bearing 13. At the forward end of the walking beam 12 there is a mulehead 14, herein referred to as the forward mulehead, bridle 15 which is attached to the polished rod 16 by a grip 17. Mounted in a conventional speed reducer 18 is a drive pulley 19 on a driven shaft 20 and also a double pitman crank 21 on the crank shaft 22. The pitmans 23 are attached to the cranks 21 by wrist pins 24. Counterweights 25 are mounted on the cranks 21 in the usual manner.

A mulehead 26 with an arcuate bearing plate 27 integral with its body 28 is mounted on the rearward end of 3,169,313 Patented Nov. 5, 1963 the walking beam 12 so that its arcuate surface is concentric with the saddle bearing 13. The purpose of the bearing plate 27 is to make the mulehead 2a wider than a conventional mulehead such as the forward mulehead 14.

A clamp 29 with bolts 3%) threaded into the bearing plate 27 at its upper end provides an attachment for depending spring steel actuating plates 31 perforated at their upper ends to receive the bolts 30. The plates 31 are in sideby-side relation, but a single plate, not shown, may be employed. The plates 31 are similarly perforated at their lower ends to receive other bolts 32 by means of which the plates are clamped between the two halves of an equalizer beam 33 which connects the two pitmans at their upper ends. As best shown in FIGURE 3, the upper ends of the pitmans 23 are connected with the ends of the equalizer beam 33 by spring steel plates 34. Plate clamps 35 and bolts 36 secure the upper ends of the plates 34 on the ends of the equalizer beam 3-3. The lower ends of the plates 34 are secured in slotted upper ends 37 of the pitmans 23 by bolts 38.

The equalizer beam 33 as illustrated is comprised of channel members 33a in back-to back relation. In the modified form of the invention shown in FIGURE 4, leaf springs 40 are positioned on opposite sides of the actuating plates 31 and between opposing faces of the beam channels 33a, and which leaf springs extend upwardly therefrom a short distance along the faces of the actuating plates 31 to reduce any stress concentration at this point. A similar leaf spring, not shown, may be secured under clamp 29 on the mulehead 28, in which arrangement the extending end of the spring would project downwardly.

In FIGURE 1 the pitman has been shown in its two most extreme angular-positions relative to the walking beam "12. By drawing a radius 39 from the point of tangency of the bearing plate 27 to the saddle bearing '13 it can be seen that the line of force exerted by the pitmans 23 is always to the effective lever arm of the walking beam 12. In the case of a conventional crank wrist pin connection, this angle could be reduced, depending on the relative lengths of the pitmans, the cranks and the walking beam. It is obvious that the power of the pumping unit will be more efiiciently delivered to the polished rod 16 by way of the walking beam 12 as long as the angle is maintained at 90. The power required to bend the plate 31 is negligible compared to the other operating loads, but on account of the elasticity of the plate it feeds back into the system as the plate straightens out on the return stroke. As compared to a hypothetical cable connection between the yoke 33 and the mulehead 26, the spring steel plate has the important advantage of a column strength on the upstroke of the pitmans 23. While the weight of the pump rod keeps the system in tension throughout the cycle under most conditions, the compressive strength of the plate 31 is an aid to overcoming the inertia of the walking beam at the beginning of the upstroke of the pitmans. This is especially true if the rearward end of the walking beam carries a counterweight 41 as is necessary in some installations. The use of the spring steel plate 31 instead of a cable connection at this point prevents backlash, which would be disastrous with the loads encountered in some pumping operations.

The invention is not limited to the exemplary constructions herein shown and described, but may be made in various ways within the scope of the appended claims.

What is claimed is:

1. In a beam type pumping unit,

a beam pivotally mounted for oscillation in a vertical plane, a crank beneath an extending end of said beam,

a mulehead on said extending end of said beam, said \mulehead including a generally vertical convex outer arcuate surface,

a pitman journalled on the extending end of said crank and extending upwardly therefrom, and

an elongate actuating plate of spring material connected at one end thereof with the upper end of the arcuate surface of said mulehead, the remaining opposite end of said plate being connected with the extending end of said pitman.

2. In a beam type pumping unit,

a beam pivotally mounted for oscillation in a vertical plane,

a pair of parallel cranks beneath an extending end of said beam,

a mulehead on said extending end of said beam, said mulehead including a generally vertical convex outer arcuate surface, pitmans journalled on the extending ends of said cranks and extending upwardly therefrom, an equalizer beam connecting the extending ends of said pitmans, and

an elongate actuating plate of spring material connected at one end thereof with the upper end of the arcuate surface of said mulehead, the remaining opposite end of said plate being connected with said 4 5. In a beam type pumping unit as defined in claim 1, the construction wherein said actuating plate has sufficient column strength to carry compression loads to overcome inertia of :the pumping unit between pumping strokes.

6. In a beam type pumping unit,

a beam pivotally mounted for oscillation in a vertical plane,

a crank beneath an extending end of said beam,

a mulehead on said extending end of said beam, said mulehead including a generally vertical convex outer arcuaite surface, the arcuate outer surface of said mulehead being defined by radius generated about the center of the pivotal mounting of said beam,

a pitman journalled on the extending end of said crank and extending upwardly therefrom, and

an elongate actuating plate of spring material connected at one end thereof with the upper end of the arcuate surface of said mulehead, the remaining opposite end of said plate being connected with the extending end of said pitman.

References Cited in the file of this patent UNITED STATES PATENTS 806,236 Brown Dec. 5, 1905 1,945,774 Goble Feb. 6, 1934 2,204,725 Crites June 18, 1940 2,706,913 Trassi Apr. 26, 1955 3,005,353 Galloway Oct. 24, 1961 3,016,753 Ziegler Ian. 16, 1962 FOREEGN PATENTS 1,306 Great Britain 1781 

1. IN A BEAM TYPE PUMPING UNIT, A BEAM PIVOTALLY MOUNTED FOR OSCILLATION IN A VERTICAL PLANE, A CRANK BENEATH AN EXTENDING END OF SAID BEAM, A MULEHEAD ON SAID EXTENDING END OF SAID BEAM, SAID MULEHEAD INCLUDING A GENERALLY VERTICAL CONVEX OUTER ARCUATE SURFACE, A PITMAN JOURNALLED ON THE EXTENDING END OF SAID CRANK AND EXTENDING UPWARDLY THEREFROM, AND AN ELONGATE ACTUATING PLATE OF SPRING MATERIAL CONNECTED AT ONE END THEREOF WITH THE UPPER END OF THE ARCUATE SURFACE OF SAID MULEHEAD, THE REMAINING OPPOSITE END OF SAID PLATE BEING CONNECTED WITH THE EXTENDING END OF SAID PITMAN. 